|Year : 1981 | Volume
| Issue : 2 | Page : 87-89
Assay of fibrin degradation products in human aqueous humour
DK Sen, GS Sarin
Department of Ophthalmology, Maulana Azad Medical College, Guru Nanak Eye Centre, New Delhi, India
D K Sen
V/4. Maulana Azad Medical College Campus, Kotla Marg, New Delhi-110002
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sen D K, Sarin G S. Assay of fibrin degradation products in human aqueous humour. Indian J Ophthalmol 1981;29:87-9
Proteolysis of fibrinogen and fibrin by plasmin results in the elaboration of fibrinogen or fibrin degradation products. Two of these fragments, D and E, comprising about 70% of the total digests share an immunological identity with the parent fibrinogen and can be detected by immunological techniques,.
The purpose of this study was to see whether these degradation products, D and E, can be detected and measured in human aqueous humour. The patients with acute nongranulomatous endogenous anterior uveitis were included because fibrin content in the aqueous humour is known to rise in those cases. The patients with senile cataract were included in the study because for ethical reasons the aqueous humour from such patients was the most normal material that could be obtained and used as control.
| Material and methods|| |
Ten patients with immature senile cataract and ten patients with acute nongranulomatous endogenous anterior uveitis were taken. All the cataract patients were otherwise normal as found by detailed local and systemic examination. The mean age of cataract patients was 47.7 years with the age ranging from 40 to 57 years. The mean age of the patients with anterior uveitis was 37.2 years with the age ranging from 22 to 50 years. The diagnosis in all the cases was established on the basis of detailed clinical examination including slit lamp biomicroscopy. The aqueous flare in the anterior uveitis cases was graded from + to ++++.
A small stab incision was made with a keratome at the limbus under local anesthesia and the aqueous humour was drawn into a tuberculin syringe fitted with a fine cannula. Care was taken not to contaminate aqueous humour with blood. The total quantity of sample obtained was approximately 200 µl. The samples wer stored at -20° Cent. until assayed.
The content of fibrin degradation product in aqueous humour was measured in all the samples using red blood cell hemagglutination inhibition immunoassay technique,,. Antifibrin-split products D and E fragments were obtained from Bahringworke, West Germany. Human fibrinogen and stablishing bovine albumin were obtained commercially. Sheep red blood cells were formalinized, tanned and sensitized with human fibrinogen by the method of Das,. Serial dilutions of both split products D and E antisera were titrated in microtitre plates with U-shaped wells using the sensitized sheep red blood cells. The split product D-antiserum showed complete haemagglutination upto the dilution of 1/6400 and split product E antiserum upto the dilution of 1/3200. Thus for further tests the above mentioned dilutions of antisera were used. Then the inhibitory tritration of human fibrinogen solution (500 μg/ml) was done in the microtitre plate by serial dilutions using both the antisera D in 1/6400 dilution and E in 1/3200 dilution. A button of cells in the centre of the wells indicated haemagglutination inhibition. The sensitivity of the test was 1.9 µg1ml of fibrinogen with both the split product D and E antisera. The test was repeated several times and each time the sensitivity was found to be the same. The technique was then applied to assay the fibrinogen degradation products in the aqueous humour. The fibrin degradation products (FDP) was calculated as given below.
| Observations|| |
In none of the patients with senile cataract the fibrin degradation products D and E in aqueous humour could be measured. However in patients with acute anterior uveitis both the products were present in considerable amount [Table - 1]. It may be seen from the table that higher fragment D and fragment E contents were associated with dense aqueous flare and lower D and E contents were associated with less aqueous flare. The mean value of fragement D was 339.8+396.5 µg/ml to 1000 µg/ml) and that of fragment E was 132.8±l57.8 µg/ml (range 7.8 µg/ml to 500 µg/ml).
| Discussion|| |
Various workers have found that the primary aqueous humour was deficient in fibrinolytic components,. Kwaan and Astrup measured the fibrinolytic activity in the aqueous of cow, sheep and pig eyes and found that it varied from species to species. In all these studies, the fibrin plate method was used to detect fibrinolysis. However, at present the amount of fibrin degradation products in a biological samyle is increasingly being taken as a reliable index of fibrinolvsis Pandolfi found high concentrations of fibrin degradation products in the aqueous humour of patients with secondary haemorrhage and commented that fibrinolysis occured in the aqueous humour in these patients. The concentration of fibrin degradation product was also studied by Bramsen and Stenbjerg in the aqueous humour from patients with Fuch's dystrophy. senile cataracts, and anterior uveitis and found them to be absent in all the samples. Our study shows that in the normal aqueous humour (obtained from patients with senile cataract) fibrin degradation product may be absent or minimal (µl.9 p/gml) but in active anterior uveitis they are present in considerable amount, The content of fibrin degradation products in aqueous humour in anterior uveitis appeared to be proportional to the density of aqueous flare. These indicate that the increased fibrin content in the aqueous humour in anterior uveitis is balanced by enhanced fibrinolytic activity in the aqueous humour. It may be regarded as the nature's attempt to keep the aqueous outflow channels free from clogging by fibrin in the aqueous humour. This might explain why there is no secondary glaucoma in many of the patients with acute anterior uveitis.
| Summary|| |
Fibrin degradation products-D and -E in human aqueous humour were measured in patients with senile cataract and acute nongranulomatous endogenous anterior uveitis by an immunological technique. These were absent in the former group but present in considerable amount in the latter. The content of fibrin degradation products in aqueous humour in cases of anterior uveitis appeared to be proportional to the density of aqueous flare, These indicate that the increased fibrin content in the aqueous humour in patients with anterior uveitis is balanced by enhanced fibrinolytic activity in the aqueous.
| Acknowledgements|| |
Our thanks are due to Dr, Kunal Saha, Associate Professor of Microbiology, Govind Ballabh Pant Hospital, New Delhi for providing us the necessary laboratory facilities for this study.
| References|| |
Nilehn, J.E, 1967 Thrombos. Diathes. haernmorrh. (Stuttg.): 18 : 487.
Nussenzweig, V.; Seigman, M.; and Grabar, P. 1961 Ann. Inst. Pasteur 100 : 490.
Das, P.C.; 1970, J. Clin. Pathol. 23 : 149.
Das, P.C.; 1970, J. Clin. Pathol. 23 : 299.
Merskey, C.; Kleiner, G.J.; and Johnson. -A.J 1966 Blood 28 1.
Pandolfi, M.; Nilsson, I.M. and Martinsson, G., 1964. Acta Ophthalmol. 42: 820:
Kimura, S., 1962, Acta Soc. Ophthalmol. Japan 66 : 1237.
Kwasan, H.C. and Astrup, T., 1963, Arch. Pathol: 76 : 595.
Pandolfi, M. 1978 Surv. Ophthalmol. 22 : 322.
Bramsen, T. and Stenbjerg, S., 1979, Acta Ophthalmol. 57:407.
[Table - 1]